Organic condensation products derived from halomethylated diaromatic ethers as well as from poly(methylol diaromatic ethers) to produce poly(methylene diaromatic ethers) are described in several U.S. patents, namely U.S. Pat. Nos. 2,911,380; 3,004,072; 3,000,839; 3,269,973 and 3,342,873. The polymers, prepared in accordance with these patents, have good thermal stability and are useful in molding potting and film forming applications. The techniques described in the literature, including the patent literature above set forth, have suffered from the by-product halogen acid produced at one stage or another. The production of the halogen acid creates a handling problem during manufacture as well as the difficulty in removing the traces of the acid from the final product. This would be especially deleterious in applications for frictional materials.
Manufacturers of brake linings currently use phenolic resins and resins made from cashew nut shell liquid (CNSL) as binders for the various asbestos and/or metal fillers involved. Thermal decomposition of these phenolic binders is the largest contributor to brake "fade" (lowering of the coefficient of friction with increasing temperature). This "fade" is a result of a molecularly thin layer of gases acting as a cushion at the brake lining/drum (or pad/rotor) interface. These gases result primarily from the decomposition of the binder. Thus, binders showing higher thermal stability should show reduced "fade."
Noise produced by the frictional material is another problem with present brake linings. Products useful as frictional materials according to the present invention show superior performance with respect to both of these problem areas.